---
title: "Lithium (Li) — element 3"
description: "Lithium is element 3, symbol Li, atomic weight 6.94. Configuration, properties, uses and neighbours."
url: https://atoneplace.net/element/lithium/
site: "At One Place"
---

# Lithium (Li)

**Lithium — element 3: Li**

6.94 u · Alkali metal · period 2, group 1

Lithium is the lightest metal and the least dense solid element — a block of it floats on water, though it reacts while doing so. It is one of only three elements made in the Big Bang, alongside hydrogen and helium, and the amount observed in old stars is about three times less than the standard cosmological model predicts, a mismatch physicists have been arguing about for forty years. Its medical use was discovered in 1949 by John Cade, who was injecting lithium urate into guinea pigs for an unrelated reason and noticed it made them placid.

## Properties

- **Atomic number:** 3
- **Symbol:** Li
- **Standard atomic weight:** 6.94 u
- **Category:** Alkali metal
- **Group:** 1
- **Period:** 2
- **Block:** s-block
- **Electron configuration:** [He] 2s¹
- **Electrons per shell:** 2, 1
- **Melting point:** 453.65 K — 180.5 °C — 356.9 °F
- **Boiling point:** 1,615 K — 1341.8 °C — 2447.3 °F
- **Density:** 0.534 g/cm³
- **Electronegativity:** 0.98 (Pauling)
- **Oxidation states:** +1
- **Discovered:** 1817 by Johan August Arfwedson

## Electron configuration

- **Full:** 1s² 2s¹
- **Noble gas shorthand:** [He] 2s¹
- **Shells:** K: 2 · L: 1

## What it is used for

- Lithium-ion cells in phones, laptops and electric cars
- Lithium carbonate as a mood stabiliser in bipolar disorder
- Lithium grease for wheel bearings and CV joints
- A flux that lowers the melting point of glass and ceramic glazes
- Aluminium-lithium alloy in aircraft structures

## Hazards

- Reacts with water to release hydrogen; stored under oil or argon
- Burning lithium cannot be put out with water or carbon dioxide
- The therapeutic and toxic blood levels are close enough to require monitoring

> IUPAC publishes an interval, [6.938, 6.997], because commercially available lithium has often been depleted of lithium-6; 6.94 is the conventional value. Material from a natural source is closer to 6.94, but reagent bottles genuinely vary.

## Neighbours in the table

| Z | Element | Symbol | Mass |
| --- | --- | --- | --- |
| 1 | Hydrogen | H | 1.008 |
| 2 | Helium | He | 4.0026 |
| 3 | Lithium ← | Li | 6.94 |
| 4 | Beryllium | Be | 9.0122 |
| 5 | Boron | B | 10.81 |

## Group 1

Elements in the same group share their outer electron count, which is why they behave similarly in reactions. Lithium sits in group 1 with hydrogen, sodium, potassium, rubidium, cesium, francium.

## Common questions

### What is the atomic number of lithium?

3. That is the number of protons in its nucleus, which is what defines the element.

### What is the symbol for lithium?

Li.

### What is the electron configuration of lithium?

1s² 2s¹, or [He] 2s¹ in noble-gas shorthand.

### What is the melting point of lithium?

453.65 K — 180.5 °C — 356.9 °F

## Related pages

- [Hydrogen (H)](https://atoneplace.net/element/hydrogen/)
- [Helium (He)](https://atoneplace.net/element/helium/)
- [Beryllium (Be)](https://atoneplace.net/element/beryllium/)
- [Boron (B)](https://atoneplace.net/element/boron/)
- [Hydrogen (H)](https://atoneplace.net/element/hydrogen/)
- [Sodium (Na)](https://atoneplace.net/element/sodium/)
- [Potassium (K)](https://atoneplace.net/element/potassium/)
- [Rubidium (Rb)](https://atoneplace.net/element/rubidium/)
- [Cesium (Cs)](https://atoneplace.net/element/cesium/)
- [Francium (Fr)](https://atoneplace.net/element/francium/)

## Sources

- Official vendor product documentation — At One Place (/about/)